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Nature- and plant-based and green-synthesized nanosilver-modified polymer nanocomposite films containing plant extracts that are not harmful to the environment and human health were produced. Green synthesis of silver nanoparticles (AgNPs) was carried out using extracts of Hemp seeds, St. John's Wort, Rosemary and Cherry Laurel plants, and these extracts were used in polymer nanocomposite. Nanocomposite films were produced by using PVA (polyvinyl alcohol) which is the most widely used and biodegradable material in the formation of biomaterials as a matrix material. The casting method was used for the production of the films. SEM/EDS methods were used to examine the morphological properties of the produced films and to analyze the size and distribution of AgNPs in the nanocomposite films. SEM studies have shown that AgNPs with spherical morphologies in a size range of 55 to 293 nm can be produced by green synthesis. XRD analysis showed (111), (200) and (202) Bragg's reflections of the face-centered cubic (fcc) structure of silver. AgNPs–Hemp–St. John's Wort nanocomposite film was the sample with the highest Shore-D hardness with a value of 49.7. Shore-D hardness and water absorption capacity tests of the produced nanocomposites were determined to be 1.86 and 1.24 times higher than the reference samples, respectively. According to antibacterial test results, films with AgNPs are much more resistant to bacterial growth than films with plant extract-added and neat films. The present study shows the importance of green-synthesized metallic nanoparticles for industrial and health applications. [ABSTRACT FROM AUTHOR]

The rapid development of nanotechnology and its applications in medicine has provided the perfect solution against a wide range of different microbes, especially antibiotic-resistant ones. In this study, a one-step approach was used in preparing silver nanoparticles (AgNPs) by mixing silver nitrate with hot Hypericum perforatum (St. John's wort) aqueous extract under high stirring to prevent agglomeration. The formation of silver nanoparticles was monitored by continuous measurement of the surface plasma resonance spectra (UV-VIS). The effect of St. John's wort aqueous extract on the formation of silver nanoparticles was evaluated and fully characterized by using different physicochemical techniques. The obtained silver nanoparticles were spherical, monodisperse, face-centered cubic (fcc) crystal structures, and the size ranges between 20 to 40 nm. They were covered with a capping layer of organic compounds considered as a nano dimension protective layer that prevents agglomeration and sedimentation. AgNPs revealed antibacterial activity against both tested Gram-positive and Gram-negative bacterial strains causing the formation of 13–32 mm inhibition zones with MIC 6.25–12.5 µg/mL; Escherichia coli strains were resistant to tested AgNPs. The specific growth rate of S. aureus was significantly reduced due to tested AgNPs at concentrations ≥½ MIC. AgNPs did not affect wound migration in fibroblast cell lines compared to control. Our results highlighted the potential use of AgNPs capped with plant extracts in the pharmaceutical and food industries to control bacterial pathogens' growth; however, further studies are required to confirm their wound healing capability and their health impact must be critically evaluated. [ABSTRACT FROM AUTHOR]